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Improving polygonal mesh,...

Started by joseMalo Nov 24, 2004 at 9:39 AM 0 replies 750+ views

Original Post

Nov 24, 2004 at 9:39 AM

Hi all, I have some characters under VRML format, I import then into my OpenGL applicantion and then I make them to move using ODE. I would like to improve (at the low level) the quality of the triangular/pligonal mesh which define these characters. Do you know where I can find some SHORT code (C/C++)with implemented methods for improving mesh quality, for example delaunay/voronoi based ? Quality measures are for example: a minimum angle inside poligons,.. control de number of poligons,.. avoid poligons of very small size,.. etc. I know that this can be done with comercial software but I Realy would like to implement it at the low level. Thanks a lots!!! /JoseMalo

grhodes_at_work

Nov 24, 2004 at 12:48 PM

jose,

See my reply to your other post on 3D Delaunay. Mr. Shewchuk also discusses 2D Delaunay, and Delaunay refinement. Guibas and Stolfi described a divide-and-conquer method for generating 2D Delaunay triangulations, and Stolfi provides working code, freeware, online. Do a google search on "Stolfi deluanay.c" to find his code. We use a custom implementation of the divide-and-conquer method to generate generalized terrain meshes.

To reduce the number of triangles I would recommend the quadric error metric decimation technique described by Garland and Heckbert (search on "Surface Simplification Using Quadric Error Metrics"). Garland provides all the details you need to implement in his Ph.D thesis titled "Quadric-Based Polygonal Surface Simplification". The thesis can be found online.

You may also be interested in using subdivision surfaces at some point, and there is a nice website, which is a companion to a book on subdivision surfaces:

Subdivision.org

There is also a website on level-of-detail, a companion to Leubke's book:

Level of Detail for 3D Graphics

Now, you asked for SHORT code... Hmmm. Don't you think that's a tall order to fill, :)?

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